Socket type electrical watt-hour meters are used to measure and indicate the amount of electrical power consumption in a residence, industry or business. Typically, a socket type watt-hour meter plugs into a meter socket using blade-like stabs or meter blade connectors located on the watt-hour meter. The meter socket itself is mounted inside a meter base or a panel. A meter socket commonly has a spring loaded receptacle-like jaw to receive and contact the watt-hour meter blade insertion. The meter jaw and spring provide a sufficient clamping force on the meter blades and conduct electricity while maintaining a certain current load and a heat rise.
Most utility companies in the United States require meter jaw guides to be installed on watt-hour meter sockets for locating the blades of watt-hour meters in the correct contact position. There are two types of material used for meter jaw guides: metal and thermal plastic. Metal meter jaw guides, are installed in pairs either on the outside or inside of line and load meter jaws. This provides a forceful guide to meter blades on effective contact position when a watt-hour meter is installed.
At this time, thermal plastic meter guides are required by most utility companies for selective ring type meter socket assemblies. A thermal plastic meter jaw guide may cover a meter jaw and may be self-retaining on the jaw. A closing slot on the receiving side of a thermal plastic meter jaw guide limits a meter blade in the slot. Therefore, thermal plastic meter jaw guides will locate the watt-hour meter in an effective contact position. Thermal plastic meter jaw guides also insulate line meter jaws from non-intentional contact. This will serve as an additional protective feature for electricians who are working with watt-hour meters without disconnecting electrical power.
One disadvantage of using thermal plastic is that the physical properties of thermal plastic show less strength and softer composition at high temperature. As a result, the thermal plastic meter jaw guide may break if excessive force is needed to insert a watt-hour meter. Therefore, some utility companies reject thermal plastic meter jaw guides and prefer metal meter jaw guides.
Another disadvantage commonly faced relates to a ring type meter covers having a reinforced return flange on the top end. The edge of the return flange, if lower than the side of supporting walls of the meter cover, may contact the bearings of line meter jaw or meter jaws during removal of the meter cover. A contact between the meter cover and “hot” meter jaw or meter jaws may cause electrical shock and/or short circuit, which may result in personal or property damage.
Therefore there is a need for improvement to provide a reliable meter jaw guide for locating meter blades in the meter jaw and to provide protection from contact with a meter jaw.